So when is the last time you saw a mud floor? Better yet, when was the last wall mud job you saw? A mud job is tile slang for a mortar work. Prior to the ‘60s most work done in the tile world was over mortar bed in what was known as a "thickset" method. Thinset was not patented till the 1950s with additional patents all the way into the early 1960s. The original patents were issued to Henry Rothberg Sr., founder of Laticrete International and Tile Council of America Labs. It took quite a few years for this new product to catch on but it was to become a pivotal point in the affordability of ceramic tile installations. To lend some real insight into how great the impact of this step on the evolutionary tile chain really was, you need only look at the sales of ceramic tile products. Shortly after World War II ceramic tile sales were pretty much confined to 4 ¼ and 6-inch wall tile, quarry tile, and mosaic tile in the 25 Million square foot range. I started in the trade around 1970. Tile products were still relatively the same though we began seeing some 8-by-8 floor tile, sales then had already reached the range of 250 Million square feet, a ten fold increase. Mortar work was still a very strong part of the installation business, probably around 50 percent or better. Now with proliferation of backer boards, membranes, and well over a hundred different thinsets, sales have reached 3.5 Billion square feet. Of this, nearly 1 Billion square feet are installed over membranes or backer boards in lieu of mortar beds. Mortar beds were also required to bond tile to a concrete slab, there was no other means of bonding tile.
Today's wooden structures do not readily lend themselves to mortar bed installations. Thickset or mud installations can be quite heavy. One inch of mortar weighs approximately 12 pounds per square foot. Most of our current code compliant residential structures allow 10 pounds per square foot as the weight of the entire structure. Very few mortar beds are only an inch in thickness, most range in the 1 ¼-inch to 2-inch range plus the weight of the tile. This type of installation system would easily require a minimum of an additional 20 pounds of load carrying capacity be added to the structure. To use an example: if you were to have a 2-by-10 floor joist in a normal residence on 16-inch centers, to meet the L/360 criteria of building code and tile installation the maximum length could be 16 feet. If you were to "beef-up" the floor system to handle our example of a mortar bed, that length would now become 13'5". Older homes, those built prior to the 1970s roughly speaking tended to be what we would today call over-built. The reasons for this change is both in the materials available and desire to value engineer today's modern homes. The current home building market is all about dollars and cents as anybody in construction knows, though, there can be some exceptions.
Mortar work is not difficult to Master, just takes some basic knowledge of sand and cement and a lot of time to practice. Those who do learn tend to have a life long preference to do mud work. Given the shortage of mud mechanics (yes, you would be a technically knowledgeable person in a manual trade; that makes you a mechanic), wages tend to be higher than those who do thinset methods exclusively. The success stories of those attending our mortar shower courses and mortar floor and wall basics are numerous and in some instances amazing to me. If our readers would like to pursue more information on the specifics of mortar floors and walls let us know and we will run an article on both or either in the future.